
and again using the product
theorem [1]},
\(J_{m}(K\overline{r}_{i}s_{i})&\approx \sum _{k=-\infty }^{\infty }J_{m-k}\left(2K\sqrt{\overline{r}\overline{r}_{0}}\cos \frac{\overline{\theta }-\overline{\theta }_{0}}{2}\right)J_{k}\left(Ka\sqrt{\frac{\overline{r}}{\overline{r}_{0}}}\sin \frac{\overline{\theta }+\overline{\theta }_{0}}{2}\cos \psi _{0}\right),\) 
